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Droughts are recurrent in southwest China due to the fragility and sensitivity of the karst environment. These events have serious impacts on local agricultural output, ecological diversity, and social stability. Understanding spatiotemporal variations and driving factors of drought in this area is of extreme importance for effective mitigation measures. The karst areas situated in southwest China were spatially divided into seven sub-regions according to the topography and degree of karst development. Drought indices, including vegetation condition index (VCI), temperature condition index (TCI), vegetation health index (VHI), normalized vegetation water supply index (NVSWI), and temperature vegetation drought index (TVDI), were calculated from MODIS data during 2000 and 2018 for each sub-region, and drought patterns were examined. The results show that droughts were found to be concentrated in sub-regions such as karst basin, karst plateau, karst gorge, and karst depression areas. Furthermore, there were more drought conditions in karst areas than in non-karst areas. In addition, improvements to drought situation in the study period are significant (p<0.05), and mitigation areas respectively account for 80.1% (NVSWI), 74.2% (VCI), 74.2% (VHI), 30.1% (TCI) and 33.2% (TVDI) of the study area, while drought expands slightly (<3.4%) in areas undergoing urban construction. Pearson's correlation coefficients between drought indices and temperature are generally above 0.5 in all sub-regions. However, the correlation coefficients between drought indices and precipitation mostly fall within the range of 0.3–0.4, indicating a weaker correlation. Our explanation for the spatiotemporal patterns of drought is that karst phenomena are the natural basis of drought and agricultural production is one of important driving forces. Positive changes of drought conditions have benefited from efforts to control rocky desertification and restore ecosystems over the past years. [ABSTRACT FROM AUTHOR]

Edible bird's nest (EBN) is the solidified saliva of swiftlet Aerodramus fuciphagus. It is an expensive premium health food that has long been consumed, especially in China. However, the broken EBN pieces left behind after the cleaning process have low market value due to high contaminants, particularly fine feathers. Thus, EBN hydrolysate (EBNH) is the best downstream product to add value to this low-grade EBN. This study aims to investigate the effects of ultrasound pretreatment on the enzymatic process of EBNH production. Initially, the EBN was treated with ultrasound at different amplitudes (30%, 60%, 90%) and times (15 min, 30 min, 45 min), then hydrolyzed for 1.5 h at 60 °C using papain enzyme (pH 7). The viscosity, degree of hydrolysis (DH), total soluble protein (TSP), anti -lipoxygenase activity and α-amylase inhibition activity of the EBNHs produced were determined. Results suggested that ultrasound amplitude exerted a more prominent effect than time in lowering the viscosity of EBNH. Viscosity of EBNH dropped by 4.4 folds–6.58 ± 0.10 mPa s after 30 min ultrasound at 90% amplitude. Under this condition, the produced EBNH exhibited 61.66 ± 2.89% anti -lipoxygenase activity and 77.40 ± 5.41% α-amylase inhibition activity, which were >100% and 43%, respectively higher than the control. However, ultrasound had exerted no significant effects on DH and TSP. These findings speculate that ultrasound enhances bioactivities of EBNH by modifying intermolecular interactions between glycopeptides and glycoproteins. This study proved that ultrasound is a promising green pretreatment technology in EBNH production. Besides, this study also provides an insight into the importance of pretreatment in bioactive EBNH production. • Ultrasound pretreatment substantially reduced viscosity of EBNH. • Ultrasound altered conformation of glycoprotein, hence EBNH bioactivities. • Ultrasound pretreatment significantly increased anti-inflammatory activity of EBNH. • Hypoglycemic activity of EBNH was doubled when ultrasound pretreatment was applied. • Ultrasound pretreatment of EBN was optimum at 90% amplitude and 30 min. [ABSTRACT FROM AUTHOR]

Phytases hydrolyze phytate to release inorganic phosphate, which decreases the requirement for phosphorus in fertilizers for crops and thus reduces environmental pollutants. This study analyzed microbial communities in rhizosphere sediment, collected in September 2012 from Shenzhen Bay, Guangdong, China, using high-throughput pyrosequencing; the results showed that the dominant taxonomic phyla were Chloroflexi, Firmicutes, and Proteobacteria, and the proportion of the beneficial bacteria, Bacillus, was 4.95 %. Twenty-nine culturable, phytase-producing bacteria were isolated, their phosphorus solubilization capacity was analyzed, and they were taxonomically characterized. Their phylogenetic placement was determined using 16S ribosomal RNA (rRNA) gene sequence analysis. The result shows that most of the isolates are members of the order Bacillales, although seven strains of Enterobacteriales, two strains of Pseudomonadales, and one strain of Oceanospirillales were also identified. The phytase gene was cloned from SPC09, Bacillus cereus, which showed the highest phosphorus solubilizing ability among the isolated strains. The gene encoded a primary translation product of 335 amino acids. A construct including the 1005-nt ORF fragment, Bc-phy, was transformed into Escherichia coli. The recombinant phytase was produced and purified, which revealed the temperature optima at 60 °C and pH optima at 6.5. The assessment by quantitative PCR (qPCR) showed an abundance of bacteria containing the Bc-phy gene; the level was generally higher in the mangrove forest than in the tidal flats and in surface soil compared to bottom soil, and the highest value was obtained in June. Herein, we report on the cloning, characterization, and activity of a novel phytase isolated from a mangrove system.